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What Is WCAG Compliance Checker?

WCAG Compliance Checker audits your color combinations against Web Content Accessibility Guidelines. It tests foreground/background pairs for contrast ratios, reports whether each combination meets WCAG AA (4.5:1 for normal text) and AAA (7:1) standards, and flags failures so you can fix accessibility issues before launch.

How to Use This Tool

Enter your foreground and background colors using hex, RGB, or HSL values. The tool calculates the precise contrast ratio and shows pass/fail results for WCAG AA and AAA at both normal and large text sizes. Test multiple combinations, adjust colors with the built-in picker, and export a compliance report. Everything runs in your browser.

Why Use WCAG Compliance Checker?

Accessibility lawsuits are increasing and WCAG compliance is a legal requirement in many jurisdictions. This tool makes contrast checking fast and visual, so you can verify compliance during design rather than after development. It’s free, instant, and requires no browser extensions or account. For a detailed walkthrough, see our step-by-step guide.

See also: Tap targets are one WCAG criterion among many; the Touch Target Checker runs the full accessibility audit.

See also: the Heading Hierarchy Checker to validate the H1-H6 outline structure that screen readers rely on.

Common Use Cases

Pre-launch audits on a marketing site where compliance with WCAG AA is a stakeholder requirement and someone needs to sign off on the actual numbers, not just "it looks fine." Reviewing a designer's color choices before they harden into the design system, where catching a 3.8:1 ratio at the comp stage is far cheaper than after engineering ships. Validating that brand colors passed down from a parent organization actually work in your context.

Auditing third-party components and widgets before integrating them into an accessibility-strict product. Documenting compliance evidence for a procurement questionnaire or a government RFP that requires a Voluntary Product Accessibility Template (VPAT). Spot-checking pages flagged by automated scanners to confirm a real violation rather than a false positive.

How We Compare

axe DevTools, WAVE, and Lighthouse run broad accessibility audits across many criteria; contrast is one of dozens of checks they perform. They're the right tool for a full audit pass. For a focused contrast check on a single color pair during a design review, the overhead of running a full audit is too much. The WebAIM contrast checker is the de facto reference and works well; this tool extends it with palette-level review, larger text rules, and bulk pairings.

The checker uses the canonical relative-luminance formula from the WCAG 2.1 spec and reports both the raw ratio and the pass/fail status against AA and AAA. It runs in the browser, so no data leaves your device. For generating a palette that passes from the start rather than auditing one that's already in use, see accessible palette generator.

Frequently Asked Questions

What is WCAG contrast ratio?+
WCAG contrast ratio measures the luminance difference between foreground and background colors. Higher ratios mean better readability. The scale goes from 1:1 (no contrast) to 21:1 (maximum contrast, black on white).
What contrast ratio do I need for WCAG AA?+
WCAG AA requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text (18px+ bold or 24px+ regular). These are the most commonly targeted compliance levels.
What is the difference between AA and AAA?+
AA is the standard compliance level (4.5:1 normal, 3:1 large text). AAA is enhanced (7:1 normal, 4.5:1 large text). Most organizations target AA. AAA provides better readability but is harder to achieve with brand colors.
How is relative luminance calculated?+
Relative luminance uses the formula L = 0.2126R + 0.7152G + 0.0722B after converting sRGB values to linear RGB. The contrast ratio is then (L1 + 0.05) / (L2 + 0.05) where L1 is the lighter color.
What WCAG version does the tool check against?+
WCAG 2.2 (the current standard as of 2024). AA and AAA contrast thresholds are both reported, with AA flagged as the legal minimum in most jurisdictions and AAA as best-practice for body text.
Does it check more than just contrast?+
Yes — alongside contrast, the tool flags missing alt text, unlabeled form fields, improper heading hierarchy, keyboard-trap risks (positive tabindex), and low-touch-target sizes (under 44x44 CSS pixels).
Can I scan an entire site or just one page?+
One page at a time via URL input. For full-site scanning, integrate axe-core or Lighthouse into your CI pipeline — this tool is designed for quick spot-checks and education.
Will it catch all accessibility issues?+
No automated tool can. Roughly 30–40% of WCAG violations are detectable automatically; the rest require human judgment (e.g., meaningful alt text, logical reading order in complex layouts). The tool covers the automated portion thoroughly.

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